Organization and Basis of Preparation (Policies)	3 Months Ended
Organization and Basis of Preparation (Policies)	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation and Reporting	Principles of Consolidation and Reporting. Our consolidated financial statements include the accounts of EPM and its wholly-owned subsidiaries. All significant intercompany transactions have been eliminated in consolidation. The consolidated financial statements for the previous year include certain reclassifications that were made to conform to the current presentation. Such reclassifications have no impact on previously reported net income or stockholders' equity.
Use of Estimates	Use of Estimates. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities at the dates of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates include reserve quantities and estimated future cash flows associated with proved reserves, which significantly impact depletion expense and potential impairments of oil and natural gas properties, income taxes and the valuation of deferred tax assets, stock-based compensation and commitments and contingencies. We analyze our estimates based on historical experience and various other assumptions that we believe to be reasonable. While we believe that our estimates and assumptions used in preparation of the consolidated financial statements are appropriate, actual results could differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2015, the FASB issued Accounting Standards Update ("ASU") 2015-14, which defers the effective date of ASU 2014-09 Revenue from Contracts with Customers (Topic 606) one year, and would allow entities the option to early adopt the new revenue standard as of the original effective date. Issued in May 2014, ASU 2014-09 provided guidance on revenue recognition on contracts with customers to transfer goods or services or on contracts for the transfer of nonfinancial assets. ASU 2014-09 requires that revenue recognition on contracts with customers depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. For public companies, ASU 2014-09 would have been effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. The standard provided for either the retrospective or cumulative effect transition method. The Company is currently assessing the impact of the adoption of ASU 2014-09 will have on its consolidated financial statements, if any. In August 2015, the Financial Accounting Standards Board ("FASB") issued ASU 2015-15, which amends presentation and disclosure requirements outlined in ASU 2015-03 (ASC Subtopic 835-30) Interest-Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs by clarifying guidance for debt issuance costs related to line of credit arrangements by acknowledging the statement by SEC staff that it would not object to presentation of debt issuance costs related to a line of credit arrangement as an asset, and amortizing them ratably over the term of the line of credit arrangement, regardless of whether there were any borrowings outstanding under the agreement. Issued in April 2015, ASU 2015-03 required debt issuance costs related to a recognized debt liability to be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts. Prior to the issuance of ASU 2015-03, debt issuance costs were required to be presented as deferred charge assets, separate from the related debt liability. ASU 2015-03 does not change the recognition and measurement requirements for debt issuance costs. ASU 2015-03 is effective for fiscal years beginning after December 15, 2015, and early adoption is permitted. The adoption of this new guidance will not have a material impact on the Company's consolidated financial statements and disclosures.